Most standard external fixation arthrodesis procedures use a prebuilt frame including two tibial rings and a foot plate with an extension, referred to as a circular fixator. A circular fixator system can be used for open or closed fracture fixation, pseudoarthrosis or nonunions of long bones, limb lengthening by epiphyseal or metaphyseal distraction, correction of bony or soft tissue deformities, or correction of segmental or nonsegmental bony or soft tissue defects. Circular Fixators have been used on long bones including: the tibia, fibula, femur, humerus, radius and ulna.
Prior to insertion of wires or pins, the circular fixator is positioned around the tibia and foot. The leg is eccentrically located in the frame to accommodate the posterior musculature, and the plantar aspect of the foot extends above or below the foot plate. To maintain the tibia and foot in position, folded up towels can be placed under the calf.
The surgeon inserts wires through the bones, and secures the wires to the frame using bolts that are inserted into holes in the rings and foot plate of the frame.
The surgeon then uses a wire tensioner to apply a desired tension to each individual wire.